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GB/T 40625-2021 (GB/T40625-2021)

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GB/T 40625-2021: PDF in English (GBT 40625-2021)
GB/T 40625-2021
ICS 43.020
CCS T 04
Indoor measurement methods for noise emitted by
accelerating motor vehicles
(ISO 362-3:2016, Measurement of noise emitted by accelerating road
vehicles - Engineering method - Part 3: Indoor testing M and N
categories, MOD)
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of
Table of Contents
Foreword ... 4 
1 Scope ... 7 
2 Normative references ... 7 
3 Terms and definitions ... 8 
4 Symbols and abbreviations ... 10 
5 Acceleration calculation methods for M1, M2 (maximum design total mass
GVM≤3500kg), N1 vehicles ... 11 
5.1 General requirements... 11 
5.2 Calculation of test acceleration ... 12 
5.3 Calculation of target acceleration ... 14 
5.4 Calculation of reference acceleration ... 14 
5.5 Calculation of partial power coefficient kp ... 14 
6 Measuring instruments ... 15 
6.1 Acoustic measuring instrument ... 15 
6.2 Speed measuring instrument ... 16 
6.3 Other measuring instruments ... 16 
7 Laboratory requirements ... 17 
7.1 General requirements... 17 
7.2 Laboratory size ... 18 
7.3 Acoustic requirements of laboratory ... 20 
7.4 Ground condition ... 20 
7.5 Cooling, ventilation, air temperature and exhaust gas management ... 20 
7.6 Laboratory background noise ... 21 
8 Chassis dynamometer requirements ... 21 
8.1 Texture type of the drum ... 21 
8.2 Drum diameter ... 21 
8.3 Dynamic test reproducibility ... 22 
8.4 Single-axis or multi-axis vehicle measurement ... 22 
8.5 Radiation noise limit of chassis dynamometer ... 23 
9 Measurement procedure ... 23 
9.1 Overview ... 23 
9.2 Microphone array - Hardware and software ... 23 
9.3 Vehicle fixing system ... 24 
9.4 Vehicle condition ... 24 
9.5 Vehicle test method ... 25 
9.6 Measurement readings and reported values ... 32 
9.7 Measurement uncertainty ... 34 
10 Test methods and test report ... 34 
10.1 General rule... 34 
10.2 Method A ... 34 
10.3 Test report ... 35 
Annex A (informative) Structural changes of this Standard compared with ISO
362-3:2016 ... 37 
Annex B (informative) List of symbols and abbreviations ... 38 
Annex C (informative) Modification plan for length of anechoic chamber ... 42 
Annex D (normative) Free field condition verification method ... 44 
Annex E (normative) Program verification method ... 48 
Annex F (informative) Evaluation of measurement uncertainty ... 52 
Annex G (normative) Measurement, evaluation and calculation of tire noise
when using Method A ... 59 
Annex H (informative) Measurement, evaluation and calculation of tire noise
when using method B ... 74 
Annex I (informative) Record table for indoor measurement methods for noise
emitted by accelerating motor vehicles ... 77 
Bibliography ... 80 
Indoor measurement methods for noise emitted by
accelerating motor vehicles
1 Scope
This Standard specifies vehicle acceleration calculation requirements for
engineering method - indoor measurement method for noise emitted by
accelerating motor vehicles, measuring instruments, laboratory requirements,
chassis dynamometer requirements, measurement procedures, test methods
and test reports.
This Standard applies to M and N category vehicles.
2 Normative references
The following referenced documents are indispensable for the application of
this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any
amendments) applies.
GB/T 3730.2, Road vehicle. Masses. Vocabulary and codes (GB/T3730.2-
1996, idt ISO1176:1990)
GB/T 3785.1, Electroacoustics - Sound level meters - Part 1: Specifications
(GB/T3785.1-2010, IEC 61672-1:2002, IDT)
GB/T 3785.3, Electroacoustics - Sound level meters - Part 3: Periodic tests
(GB/T 3785.3-2018, IEC 61672-3:2013, IDT)
GB/T 5910, Passenger cars. Mass distribution (GB/T 5910-1998, idt
GB/T 6882-2016, Acoustics - Determination of sound power levels and
sound energy levels of noise sources using sound pressure - Precision
methods for anechoic rooms and hemi-anechoic rooms (ISO 3745:2012, IDT)
GB/T 15089, Classification of power-driven vehicles and trailers
GB/T 15173-2010, Electroacoustics - Sound calibrators (IEC 60942:2003,
The vehicle shall be fixed on the drum. Make, in the whole test process, the
error of the distance between the center line CC' of the vehicle and each
microphone array ±0.05m.
Pre-acceleration shall be used to ensure that the vehicle obtains a more stable
acceleration within the acceleration calculation distance.
If the trailer cannot be separated from the tractor, the trailer shall be ignored
when passing the virtual line BB'. If the vehicle is equipped with more than two-
wheel drive devices, please select the drive mode used on normal roads for
testing. If the vehicle is equipped with an auxiliary manual transmission or
multiple gear shafts, then the position for normal city driving shall be used. In
all cases, avoid the use of gear ratios for slow motion, parking or braking. Speed selection requirements
The test speed vtest shall be 50km/h±1km/h. When the vehicle reference point
is on the virtual line PP', the test speed vtest shall be reached. If the test speed
is modified according to the requirements of, the modified test speed
shall be used for both acceleration and constant speed testing.
Avoid vehicle skidding during measurement. To avoid excessive skidding, it is
advisable to control the engine speed and vehicle speed ratio between the
acceleration phase and the constant speed state. Gear selection requirements General requirements
The measurement gear is determined according to the relationship between the
test acceleration awot test and the reference acceleration awot ref that can be
achieved when the acceleration device is fully opened.
For test vehicles equipped with different transmission software programs or
common driving modes (such as sports mode, winter mode, and adaptive
mode), the automobile manufacturer shall provide instructions and verification.
The acceleration value of the mode used by the test vehicle in the measurement
is closest to awot ref. For test vehicles equipped with devices or equipment capable of
locking the gear ratio
Gear selection shall meet the following conditions:
a) If the gear i test acceleration value awot test,i does not exceed the test
acceleration upper limit awot max, and the difference with the reference
acceleration awot ref is within ±5% of awot ref, then use this gear to measure.
vehicle speed vtest when reaching the target engine speed condition is
higher than 50km/h, then gradually reduce its target speed condition with
5% maximum net power speed until the gear i+1 vehicle speed vtest is not
higher than 50km/h.
NOTE: Additional devices or equipment can be used to lock the gear ratio. For vehicles that cannot lock the gear ratio for measurement
The gear selector shall be placed in the fully automatic control position. During
the measurement process, the driver shall ensure that the vehicle can shift to a
lower gear with greater acceleration. However, it is not allowed to shift to a
higher gear with a lower acceleration (except after the vehicle reference point
passes through line BB'). Electronic or mechanical devices are allowed to
prevent the vehicle from downshifting to a gear that is not commonly used when
driving on the road during the measurement process. If the engine target speed
condition can be met, then the gear selection refers to If the engine
target speed condition cannot be met, then only the target vehicle speed
condition is considered when measuring, and vtest is within the range of
35km/h±5km/h. If the target vehicle speed condition can be met during the
measurement process, then use this speed for measurement. If the target
vehicle speed condition cannot be met, then two conditions are measured: One
is that the exit speed vtest is within the range of 40km/h~45km/h; The other is
that vtest is in the range of 25km/h~30km/h. If the speed condition of vtest in the
range of 25km/h~30km/h still cannot be achieved, then only measure in the
range of vtest of 40km/h~45km/h. Record the maximum sound pressure level of
the vehicle passing through the measurement area. Powertrain without rotating engine speed
For vehicles equipped with a powertrain system without rotating engine speed,
only the vehicle speed vtarget BB' is required to meet the target condition.
The following conditions can be used to meet the target vehicle speed vtarget BB'
a) If the engine speed requirement cannot be met, then only the target
vehicle speed vtarget BB' needs to be met;
b) If neither the target engine speed nor the target vehicle speed vtarget BB'
requirements can be met, then the following two test conditions shall be
carried out:
The target vehicle speed vBB'1 of the first test condition shall meet the
requirements of formula (15) and the target vehicle speed vBB'2 of the
second test condition shall meet the requirements of formula (16):
(Above excerpt was released on 2022-01-06, modified on 2022-01-06, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/GBT40625-2021